Preheat oven to 350°F.
Thoroughly grease a 12 cup Bundt cake pan.
In large bowl combine all purpose flour, rice flour, poppy seeds, baking powder and salt; set aside.
In large bowl with mixer at medium speed, beat butter and sugar together until very light and fluffy. Beat in eggs one at a time; stir in sour cream and grated lemon rind.
Gradually stir in flour mixture about 1 cup at a time until thoroughly combined.
Spoon batter into prepared Bundt pan; bake on middle shelf of preheated oven for about 55 to 65 minutes or until toothpick inserted comes out clean.
Remove from oven and allow cooling in pan for about 15 minutes then removing cake from pan and setting on wire rack to cool completely.